We got a customer asking about how to use rowing data in order to improve the coaching of the recovery for a crew.
“I think the important factor is making the recovery as smooth as possible so we don’t lose too much boat speed in the 8+. We have spent a lot time optimising the power stroke and have now moved on to the recovery. The boat telemetry shows a dip in speed during the recovery. This loss of speed is not constant. They are working on reducing the dip and maintaining acceleration for longer. “
This is obviously a fairly complicated area. And so we approached Al Isherwood of Coxmate for his insight using the Coxmate software (this works with the Coxmate GPS and the Coxmate SX products).
- Attachment 1 shows a summary of a training session using the Coxmate GPS and then graphing the stroke rating (red), speed (blue) and acceleration (light blue). There is obviously a lot of information and it does not immediately make sense
Coxmate PC analysis Attachment 1[/caption]
- From this data you can select a portion of the session or a race and then save this as a separate file for analysis. This is then available as a race summary on attachment 2. This summary can be displayed in split intervals ranging between 50m and 1000m
Coxmate PC Analysis attachment 2[/caption]
- Attachment 3 I have zoomed in on the summary data and again shown is rating (red), velocity (blue) and acceleration (light blue). The focus here is the acceleration profile.
Attachment 3 Coxmate PC Software detail
- Attachment 4 working left to right with the yellow marks shows the catch, the release and then the next catch. The flat light blue line reflects average acceleration so is a reference point
- The red circle is the velocity (speed of the boat) and as you can see the acceleration of the boat is negative after the release (2nd yellow mark) which is reflected in the velocity trace with a slight dip. However as you can see there is good acceleration in the second half of the recovery and the velocity curve indicates that the boat actually increases in speed as the recovery continues
Attachment 4 Coxmate PC analysis software
- Without going into too much detail, if you use the average acceleration line as a reference the more you can keep the acceleration curve around the average line (avoiding dips) on the recovery the better a job you are doing.
Coaching for the recovery
For a coach it would be worth playing around with crew members, set up (oar length, position relative to pin etc) in a methodical and controlled way to assess the way the boat moves. It is crucial that the “scientific method” is employed and all other variables are controlled for during such a process to ensure the data is as objective as possible.
It is important that the assessment of the crew’s performance is done at indicative race rates to ensure relevance to competition performance. If you are intending to do a test-retest assessment then rating 28 is crucial. Short pieces of 500m-1,000m will suffice as you do not want athletes to be too fatigued when assessing set up.
Another way to look at this data is to compare the variation between the peaks and dips in the velocity and acceleration curves however this would need to be a video as writing about it would end up being a thesis!
For your reference the white vertical line shown in attachments 3 & 4 is a cursor that can be moved along the graph. At any point it will display the relevant data in the top bar.
In attachment 3 this is:
- X axis: Time at 31:58.38 in to the session
- Rating: 24.33
- Speed: at that point in the stroke it is on 1:55.7/500m pace
- Distance per stroke: 9.69m
- Heart Rate: 171.62
Drills for coaching the recovery
My personal favourites are drills where the crew can learn to both improve the ratio (contrast between the power phase and recovery phase of the stroke) and also increase their bodily relaxation. So if you can work harder in the power phase with a greater acceleration and also rest more with muscle relaxation on the recovery this becomes more sustainable in both phases.
Read 7 Rowing Exercises to Prevent Rushing the Slide from which I’ve extracted these two as being particularly pertinent.
- Read this expert article by Troy Howell of Craftsbury Sculling Centre about teaching ratio and rhythm
- And this one about coaching a long stroke – by taking the focus away from the rush and coaching the long stroke you can improve the acceleration in the power phase and reduce the deceleration in the recovery phase.